JPH1118499A - Sensorless revolution control method for permanent magnet type synchronous motor and step-out detection method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method by which a magnetic axis can be appointed, even in a low revolution range and a revolution can be controlled satisfactorily. SOLUTION: A control method includes a δ-axis revolution controller 1, δ-axis and γ-axis current controllers 2 and 3, a vector control circuit 4 and an inverter circuit 5 and a motor revolution is calculated, in accordance with the currents of two phases of a synchronous motor 6. For that purpose, an α-βspace coordinate system, consisting of an α-axis which is the U-phase of the stator of the motor 6 and a β-axis which is an axis turned from the α-axis in a positive direction by an electrical angle of 90 degrees, is set. Coordinates d-q axes, consisting of the real magnetic axis of the motor 6 as a d-axis and a q-axis which leads the d-axis by 90 degrees and rotating at a motor revolution ωrm and coordinates γ-δ axes, consisting of the appointed magnetic axis of the motor as a γ-axis and a δ-axis which leads ahead the γ-axis by 90 degrees and rotating at a motor command revolution ωrm * are set in the α-β space coordinate system. By making a current command iγ* in the γ-axis direction positive, a torque by which the d-axis bound to the γ-axis is generated and a current command iδ* in the δ-axis direction is obtained, in accordance with a deviation between the revolution command and an estimated revolution ωrm *.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensorless speed control method for a permanent magnet synchronous motor using a permanent magnet as a rotor and a method for detecting a step-out of the motor.

[0002]

2. Description of the Related Art Brushless DC using a permanent magnet as a rotor
When the motor is operated as a synchronous motor, it is necessary to obtain the absolute value of the rotor and perform accurate current control. In order to obtain the absolute value of the rotor, it is common to use a rotating position detector such as an encoder or a resolver.However, since there are problems with wiring and structural complexity, price and operating environment, etc. There has been proposed a sensorless vector control method for obtaining a magnetic pole position of a rotor without using a position detector.

As a conventional sensorless vector control of a synchronous motor, there is a method described in Japanese Patent Application Laid-Open No. 8-308286, which uses a γ set on a magnetic pole of a rotor.
A stator current iγ, iδ converted into a −δ-axis coordinate system;
The difference between the previously estimated current estimated values iγ _est and iδ _est and γ
Voltage command Vγ converted into -δ-axis coordinate system, as input V8, current i? _Est in gamma-[delta]-axis coordinate system, i? _Est and the induced voltage εγ _est, εδ _{e st} and the speed of the rotor omega _Rmest
Is estimated.

Further, γ estimated by the above method is
Estimated value of shaft induced voltage εγ _est and estimated value of rotor angular velocity ω
_{From rmest} , the deviation angle θ between the dq coordinate set on the permanent magnet of the rotor and the γ-δ coordinate is estimated, and the rotor position is corrected.

[0005] Vector control is performed using the angular velocity and magnetic axis position information estimated by the above method.

[0006]

However, in the prior art, as the synchronous motor rotates at a low speed, the synchronous motor induced voltage decreases, and the estimation accuracy of the magnetic axis deteriorates. When control is implemented,
There was a drawback that the magnetic axis was lost and control was lost.

Further, in the above-mentioned conventional method, γ-δ
When the deviation angle θ _e between the shaft and the dq axis becomes large and the control becomes impossible, the synchronous motor loses synchronism, and there is a possibility that the synchronous motor and a mechanical system connected thereto may be damaged.

Accordingly, it is a first object of the present invention to provide a control method capable of designating a magnetic axis even in a low speed range and capable of excellent speed control.

Further, the present invention provides a method for accurately estimating induced voltages εγ and εδ generated on the γ-δ axis and comparing the induced voltage estimated values εγ _est and εδ _est to detect a step-out state. Subject.

[0010]

In order to solve the first problem, the present invention provides a δ-axis speed controller for outputting a δ-axis current command from a deviation signal between a speed command and a motor speed;
A δ-axis current command and a γ-axis current controller that respectively calculate a δ-axis voltage command and a γ-axis voltage command from an axis current command and a γ-axis current command. A vector control circuit that outputs a voltage command phase, an inverter circuit that supplies a drive current to the synchronous motor based on the voltage command absolute value and the voltage command phase, and the motor speed is determined based on two-phase current of the synchronous motor. In the sensorless speed control method for a permanent magnet type synchronous motor to be operated, an α-β space coordinate system is set in which the U-phase of the stator of the synchronous motor is an α axis, and an electrical angle from the α axis is an electrical angle of 90 ° and a β axis is a positive rotation direction. In the α-β space coordinate system, the true magnetic axis of the synchronous motor
座標 The advanced axis is the q axis, the coordinate dq axis rotating at the synchronous motor rotation speed ω _rm , and the designated magnetic axis of the synchronous motor are the γ axis and γ
An axis advanced by 90 ° from the axis is set as the δ axis, a γ-δ axis that rotates at the synchronous motor rotation command speed ω _rm ^* is set, and the current command iγ ^* in the γ axis direction is made positive, so that the d axis is changed. Generates a torque for restricting to the γ-axis, and issues a δ-axis direction current command iδ ^*.
Is derived by feedback control that multiplies a gain between a speed command and a speed estimation value ω _rm ^* derived from a disturbance observer created from a δ-axis current equation as a synchronous motor induced voltage disturbance by a gain.

In order to solve the second problem, a second invention provides a method for calculating δ from a deviation signal between a speed command and a motor speed.
Δ-axis speed controller that outputs a shaft current command, a δ-axis current controller and a γ-axis current controller that respectively calculate a δ-axis voltage command and a γ-axis voltage command from a δ-axis current command and a γ-axis current command, a vector control circuit that outputs a voltage command absolute value and a voltage command phase based on a γ-axis voltage command; an inverter circuit that supplies a drive current to a synchronous motor based on the voltage command absolute value and the voltage command phase; A speed calculating means for calculating based on two-phase currents of the synchronous motor; and dq coordinate axes having a true magnetic axis of the rotor as a d axis, and γ assumed on the rotor.
In the step-out detection method of the permanent magnet type synchronous motor that controls so that the -δ axis coincides, the time k · T _s (where k =
0, 1, 2, 3,..., And T _s are sampling times), a stator current for at least two phases supplied to the synchronous motor is detected, and the stator current is converted into a γ-δ coordinate system to obtain γ. Axis current iγ (k) and δ axis current iδ (k)
Γ-axis current iγ (k) and δ-axis current δ
(K) and the γ-axis current iγ estimated in the previous control loop
_est (k) and difference iγ (k) between δ-axis current iδ _est (k)
−iγ _est (k) and iδ (k) −iδ _est (k) are correction amounts, and the voltage command value Vγ converted to the γ-δ axis coordinate system
^* (K) and Vδ ^* (k) as inputs, and the induced voltage εγ of the γ axis generated by the rotation of the rotor of the synchronous motor
(K) and [delta] induced voltage .epsilon..DELTA (k) of the shaft, constitutes a state estimator as disturbance to current response when the rotor is not rotating, the time (k + 1) · T _s seconds gamma-[delta]-axis coordinates estimating the current iγ _est (k + 1) and iδ _est (k + 1) and induced voltage εγ _est (k + 1) and εδ _est (k + 1) in the system, from the estimated induced voltage εγ _est (k + 1) and εδ _est (k + 1) Step out is detected.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a sensorless speed control method, when a positive direct current iγ flows through an arbitrary designated axis γ-axis, the phase is delayed by a load angle θ _e from the true magnetic axis d-axis and the γ-axis. Assuming that there is a phase difference between
A torque in the γ-axis direction proportional to nθ _e is generated.
For this reason, when the load torque is 0, the true magnetic axis always receives a torque directed toward the designated magnetic axis γ-axis. However, a synchronous machine having no normal braking winding has a damping factor of almost 0.
Therefore, the d axis generates a simple vibration around the γ axis. In the invention according to the first aspect, transient vibration of the d-axis is suppressed by setting the current command value derived from the speed estimation value feedback as the δ-axis current. On the other hand, the disturbance estimation value εγ _est derived from the γ-axis current equation estimates ε sin θ _e when the induced voltage of the synchronous motor is ε. For this reason, when the load angle is small, εγ _est is a value proportional to the load angle. In the present invention, since the correction current command iδθ ^* obtained by proportionally integrating the disturbance estimation value εγ _est is added to the δ current command, the correction current flows until εγ is 0, that is, the γ axis coincides with the d axis. Therefore, as a result, the γ axis coincides with the magnetic axis d axis, and since the γ axis rotates at the command speed, the true magnetic axis d axis also rotates at the command speed.

In the invention according to claim 2, the time k ·
T _s at (where, k = 0, 1, 2, 3, ..., T _s is the sampling time) to detect at least two phases of the stator current supplied to the permanent magnet synchronous motor, the setting on the rotor By converting to the γ-δ coordinate system, the γ-axis current iγ
(K) and δ-axis current iδ (k) are derived, and the previously derived γ-axis current estimated value iγ _est (k) and δ-axis current estimated value iδ
_{Using est} (k) and voltages Vγ (k), Vδ (k), a state equation in the γ-δ axis coordinate system of the permanent magnet type synchronous motor

(Equation 1) _{However, εγ = -sinθ e (ω rm} / Lq) ψ mag εδ = cosθ e (ω m / Lq) ψ mag R s: stator resistance, L _q: q axis inductance,
L _d : d-axis inductance, θ _e : shift angle between γ-δ axis and dq axis, ω _rm : rotor angular velocity, ψ _mag : magnetic flux generated by permanent magnet, εγ and εδ have sufficient time change. Configured as small.

A state estimator

(Equation 2) However, “＾” represents an estimated value, and has the same meaning as the subscript “est”.

Has been expanded to a discrete value system

(Equation 3) The current estimated value iγ _est at time (k + 1) T _s seconds
(K + 1), iδ _est (k + 1), estimated value of induced voltage εγ
_est (k + 1), determine the εδ _est (k + 1), using the coefficient Kθ for determining the allowable range of the deviation angle theta _e of gamma-[delta] axis and d-q axis,

(Equation 4) When the condition is satisfied, the step-out state is set.

[0016]

Embodiments of the present invention will be described below.

FIG. 1 is a block diagram showing a control system of a synchronous motor to which an embodiment of a magnetic pole position / speed estimation method according to the present invention is applied, and FIG. 2 is a flowchart showing processing in the embodiment.

The control system block diagram of FIG. 1 will be described. In the figure, 1 is a speed controller, 2 is a δ-axis current controller, 3 is a γ-axis current controller, 4 is a vector control circuit, 5 is an inverter circuit, 6 is a synchronous motor, 7 is a phase converter, and 8 is γ-δ. An axis current / induced voltage estimator, 9 is an angular velocity deriver, 10 is an offset angle deriver, 11 is a γ-δ axis position corrector, 12 is a γ-axis / δ-axis current corrector, and 13 is a δ-axis current command corrector. is there.

The angular velocity command ω _rm ^* and the estimated angular velocity ω _rmest are input to the speed controller 1, and the speed controller
δ-axis current command iδ ^* is output. Also, εγ _est is input to the δ-axis current command corrector 13 and the δ-axis corrected current command iδθ
Output ^* . The δ-axis current controller 2 has iδ ^* and iδθ
^* And the estimated δ-axis current value _{iδ est2} , and outputs a δ-axis voltage command Vδ ^* . On the other hand, the γ-axis current command _iγ ^* and the γ-axis current estimated value _{iγ est2} are input to the control circuit 4, and the absolute value of the voltage value (Vδ ² + Vγ ² ) ^1/2 and the phase tan ^{− in} the voltage output direction from the γ-axis. ¹ (Vδ / Vγ) is input to the inverter circuit 5 and firing is performed.

On the other hand, the γ-δ axis current / induced voltage estimator 8
Is the stator current i _u and i _v a phase converter 7 of the synchronous motor 6
Γ-axis current iγ and δ-axis current iδ obtained through
Input the position of the δ axis and the voltage commands Vδ ^* , Vγ ^* , and (1)
The calculation of the equation is performed, and the γ-δ axis current estimated values iγ _est , iδ
_est and the γ-δ axis induced voltage εδ _est are output. εδ _est
Is input to the angular velocity deriving unit 9 and the equations (2) and (3) are executed to derive the estimated angular velocity ω _rmest .
Further, the speed command value ω _rm ^* is input to the γ-δ axis position corrector 11, and the position correction of the γ-δ axis is executed by the equation (4).

[0021]

(Equation 5)

(Equation 6)

(Equation 7)

(Equation 8) Next, the braking operation will be described with reference to the flowchart of FIG. At least k-phase currents supplied to the synchronous machine at k · T _s seconds, for example, i _u (k) and i _v (k) are detected (step S1), and γ-δ corrected in the previous loop is detected. It is converted to an axial coordinate system to derive iγ (k) and iδ (k) (step S2). Voltage command Vγ converted to γ-δ coordinate system
^* (K) and Vδ ^* (k) are input (step S3), and the estimated value iγ at (k + 1) · T _s seconds is obtained by equation (5).
_{est (k + 1), iδ} est (k + 1), εγ e st (k +
1) derive εδ _est (k + 1) (step S
4). The sign of the angular velocity is determined from the estimated sign of εδ _est (k + 1) (step S5), and this sign and ε
From the sum of squares of γ _est (k + 1) and εδ _est (k + 1), ω
_rmest (k + 1) is derived (step S6). (8)
The position of the γ-axis is corrected by the equation. (Step S7).

FIG. 3 is a block diagram showing a control system for a synchronous motor to which one embodiment of the step-out detection method of the present invention is applied, and FIG. 4 is a flowchart showing a digital control operation for step-out detection.

The control system block diagram of FIG. 3 will be described. In the figure, 14 is a step-out detector, and 15 is a protection operation detection circuit. The same components as those of the embodiment shown in FIG.

The angular velocity command ω _rm ^* and the estimated angular velocity ω
_rmest is input to the speed controller 1, and the speed controller 1 outputs a δ-axis current command iδ ^* . δ axis current controller 2 inputs the i? ^* and the δ-axis current estimated value i? _est 2, and outputs a δ-axis voltage command V8 ^*. On the other hand, the γ-axis current command iγ ^* and the γ-axis current estimated value iγ _est 2 are input to the γ-axis current controller 3, and the γ-axis current controller 3
The shaft voltage command Vγ ^* is output. The voltage commands Vδ ^* , Vγ ^*, and the γ-δ-axis position output from the γ-δ-axis position corrector 11 are input to the vector control circuit 4 and the voltage value absolute value (Vδ ²
+ Vγ ² ) ^1/2 and phase tan ^{−1 in} the voltage output direction from the γ axis
(Vδ / Vγ) is input to the inverter circuit 5 and firing is performed.

On the other hand, the γ-δ axis current / induced voltage estimator 8
Is the stator current i _u and i _v a phase converter 7 of the synchronous motor 6
Γ-axis current iγ and δ-axis current iδ obtained through
Input the position of the δ axis and the voltage commands Vδ ^* , Vγ ^* , and (3)
The calculation of the equation is performed, and the γ-δ axis current estimated values iγ _est , iδ
_est and the γ-δ axis induced voltages εγ _est and εδ _est are output. These εγ _est and εδ _est are input to the out-of-step detector 14, and the out-of-step is detected by executing the equation (4).
When the step-out is detected, the protection operation detection circuit 15 is notified of the abnormality detection.

Next, the control operation will be described with reference to the flowchart of FIG. At least two phases of current supplied to the synchronous machine at k · T _s seconds, for example, i _u (k), _iv (k)
Is detected (step S11), converted to the γ-δ axis coordinate system corrected in the previous loop, and iγ (k) and iδ (k) are derived (step S12). The voltage commands Vγ ^* (k) and Vδ ^* (k) converted into the γ-δ coordinate system are input (step S13), and the estimated value iγ _est (k + 1) · T _s seconds is obtained by equation (7). _{k + 1), iδ est (} k + 1), εγ est
(K + 1) and εδ _est (k + 1) are derived (step S14). The estimated εγ _est (k + 1) and εδ _est (k
+1) satisfies Equation (8) (step S15). If so, step-out detection is reported to the protection operation detection circuit (step S16).

[0027]

As described above, according to the sensorless speed control method of the present invention, since the γ axis coincides with the magnetic axis d axis and the γ axis rotates at the command speed, the true magnetic axis d axis Also rotates at the command speed, so that good speed control is possible even in a low speed range.

According to the step-out detection method of the present invention, the γ-axis induced voltage, δ, which is a function of θe generated on the γ-δ axis set on the rotor to rotate at the estimated speed ω _rmest ,
Because it constitutes a state estimator that estimates the shaft induced voltage,
By sequentially comparing the two estimated values, a step-out of the synchronous motor can be detected, and damage to the synchronous motor and a mechanical system connected thereto can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a control system for a synchronous motor according to an embodiment of the present invention.

FIG. 2 is a flowchart of the present invention in a discrete value system.

FIG. 3 is a block diagram showing a control system for a synchronous motor according to one embodiment of the present invention.

FIG. 4 is a flowchart of the present invention in a discrete value system.

[Explanation of symbols]

1 speed controller, 2 δ-axis current controller, 3
γ-axis current controller, 4 vector control circuit, 5
Inverter circuit, 6 synchronous motor, 7-phase converter, 8
γ-δ axis current and induced voltage estimator, 9 angular velocity deriving device, 1
0 shift angle deriving device, 11 γ-δ axis position corrector, 12
γ-axis / δ-axis current corrector, 13 δ-axis current command corrector, 1
4 step-out detector, 15 protection operation detection circuit

Claims (2)

[Claims] 1. A δ-axis speed controller that outputs a δ-axis current command from a deviation signal between a speed command and a motor speed, and calculates a δ-axis voltage command and a γ-axis voltage command from a δ-axis current command and a γ-axis current command, respectively. δ-axis current controller and γ-axis current controller, a vector control circuit that outputs a voltage command absolute value and a voltage command phase based on the δ-axis voltage command and the γ-axis voltage command, based on the voltage command absolute value and the voltage command phase A sensorless speed control method for a permanent magnet type synchronous motor, comprising an inverter circuit for supplying a drive current to the synchronous motor, and calculating the motor speed based on two-phase currents of the synchronous motor. Set the α-β space coordinate system in which the phase is the α axis and the electric axis is 90 ° from the α axis in the positive rotation direction, and set the true magnetic axis of the synchronous motor in the α-β space coordinate system. d
Axis, an axis advanced by 90 ° from the d axis is defined as a q axis, a coordinate dq axis rotating at a synchronous motor rotation speed ω _rm , and a designated magnetic axis of the synchronous motor is a γ axis, and an axis advanced by 90 ° from the γ axis is defined as Set the δ-axis, the γ-δ axis that rotates at the synchronous motor rotation command speed ω _rm ^* , and set the current command iγ ^* in the γ-axis direction to be positive, so that the torque for restraining the d-axis to the γ-axis The gain is multiplied by the difference between the δ-axis current command iδ ^* , the speed command, and the speed estimation value ω _rm ^* derived from the disturbance observer created from the δ-axis current equation as the synchronous motor induced voltage disturbance. A sensorless speed control method of a permanent magnet type synchronous motor derived from control. 2. A δ-axis speed controller that outputs a δ-axis current command from a deviation signal between a speed command and a motor speed, and calculates a δ-axis voltage command and a γ-axis voltage command from the δ-axis current command and the γ-axis current command, respectively. δ-axis current controller and γ-axis current controller, a vector control circuit that outputs a voltage command absolute value and a voltage command phase based on the δ-axis voltage command and the γ-axis voltage command, based on the voltage command absolute value and the voltage command phase An inverter circuit for supplying a drive current to the synchronous motor; speed calculating means for calculating the motor speed based on a two-phase current of the synchronous motor; dq coordinate axes having a true magnetic axis of the rotor as a d axis In a step-out detection method for a permanent magnet type synchronous motor that controls the γ-δ axes assumed on the rotor to coincide with each other, a time k · Ts (where k = 0, 1, 2, 3,...) , T _s
At the sampling time), a stator current for at least two phases supplied to the synchronous motor is detected, and the stator current is converted into a γ-δ coordinate system, thereby obtaining a γ-axis current iγ
(K) and the δ-axis current iδ (k) are derived, and these γ-axis currents iγ (k) and δ-axis current δ (k) and γ-axis currents iγ _est (k) and δ-axis current i
Difference from δ _est (k) iγ (k) −iγ _est (k) and i δ
(K) −iδ _est (k) is a correction amount, and the voltage command values Vγ ^* (k) and Vδ ^* (k) converted into the γ-δ axis coordinate system are input and the rotor of the synchronous motor is rotated. Induced voltage εγ (k) and δ induced voltage εδ (k)
Is constructed as a disturbance to the current response when the rotor is not rotating, and the currents iγ _est (k + 1) and i in the γ-δ axis coordinate system in time (k + 1) · T _s seconds
_est (k + 1) and induced voltages εγ _est (k + 1) and εδ _est (k + 1) are estimated, and a step-out is detected from the estimated induced voltages εγ _est (k + 1) and εδ _est (k + 1). For detecting out-of-step of a permanent magnet synchronous motor.